1. Field of the Invention:
This invention relates in general to monolithically integrated bipolar Darlington circuits and in particular to a novel circuit.
2. Description of the Prior Art:
The article "Power Bipolar Devices" by Ph.Leturcq in the periodical "Micro-Electronic Realiability" Volume 24, No. 2 1984, pages 313-337 including FIG. 16 on Page 333 discloses a monolithically integrated circuit. Depending on the switch on of the base current which is generated by a base current source connected between the base terminal and the emitter terminal, collector current is switched on in the switch mode and the collector current flows in an external load circuit connected to the emitter and to the collector terminal. Important parameters in the switch on of the collector current are the turn-on delay times t.sub.d and the rise time t.sub.r of the collector current. Defined as the time which is between the time when the base current reaches 10% of its maximum value and the time when the collector current reaches 10% of its final value is t.sub.d. The time which is required for the rise of the collector current from 10% to 90% of its final value is t.sub.r. When for the purpose of shutting the collector current off, the base current is reversed in direction then the collector current also begins to drop after a so-called storage time t.sub.s and this is then followed by a drop time t.sub.f in which the collector current drops from 90% of its final value to 10% of its final value.
In high voltage applications, for example, in the inhibited conditions of the Darlington circuit, a collector voltage of 1000 volts or more can exist between the emitter and the collector terminal and a collector current of, for example, 100 amps flows in the load circuit in the conductive condition such that a residual voltage of, for example, two volts occurs between the emitter terminal and the collector terminal of the output transistor.